Rim curling mechanism for containers



NOV. 27,1962 5;, Lo s 3,065,677

RIM CURLING MECHANISM FOR CONTAINERS Filed July 20, 1959 2 Sheets-Sheet 1 .F/li

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DOA/HAO 5 .aisae BY 6 WWI am ArraeA/E-YJ Nov. 27, 1962 D. B. LOESER RIM CURLING MECHANISM FOR CONTAINERS 2 Sheets-Sheet 2 Filed July 20, 1959 .m y Z 16 M M ll/ United States Patent 3,065,677 RIM CURLING MECHANISM FOR CONTAINERS Donald B. Loeser, Thiensville, Wis., assignor to Paper Machinery Corporation, Milwaukee, Wis., a corporation of Wisconsin Filed July 20, M59, Ser. No. 828,272 1 Claim. (Cl. 93-365) This invention relates generally to machines for making containers, such as for example, paper cups, and more specifically relates to mechanism for forming an edge bead or rim on the top of the containers. I

Conventional bead rolling mechanisms of this general character have heretofore been used in which complementary dies are moved toward one another to curl the top edge of the cup, which is located between the dies, into a bead. Some of these prior art devices have proposed to radially expand the upper portion of the cup into a cylindrical shape before curling the bead therefrom, in an attempt to be able to better control the edge during bead formation and form a reinforced, uniform and compact bead.

- Many of these conventional rim curling mechanisms have utilized complementary, curved dies in which the lower die is first moved upwardly around the upper end of the cup and to the top edge of the cup where it firmly holds the cup top against a male die. Then the upper die is moved downwardly to engage the uppermost edge of the cup between the dies and then they both move together down a portion of the cup to form the curled edge. These devices have proved successful but have also had several shortcomings, for example, the successive movement of each of the dies relative to one another and then together requires a considerable number of dies and associated parts to actuate them; other latching devices have also been necessary to hold the lower die in position after the curling operation to permit separation of the dies; some dies required costly and ditficult to machine contours in order to accommodate various conditions, and types of paper; sulficient cooling time could not always be provided due to the necessity of rapidly indexing to the next station; and the operation of separating the dies often caused the bead to unroll and loosen to a certain extent.

Accordingly, the present invention provides a rim curling mechanism in which the above shortcomings have been eliminated.

By means of this invention a rim curling mechanism has been provided in which a tight and compact bead is formed in one operation and with the bottom rim curling die fixed on the top of the cup body fem-ale anvil and held in a stationary position during the curling operation. The head is formed simply by a single downward pass of the upper curling die, the bead so formed is held from uncurling by the size and shape of the wall of the lower die, furthermore, the shape is such that the bead actually tends to tighten as the cup is subsequently ejected from the female anvil.

The construction and operation of the die mechanism is such that the dies can handle material of widely different conditions and characteristics; and can be used in either cold or hot types of bead forming operations.

These and other objects and advantages of the present invention will appear hereinafter as this disclosure progresses, reference being had to the accompanying drawings, in which:

FIGURE 1 is a fragmentary, elevational, cross sectional view through the rim curling station of a cup making machine embodying the present invention;

FIGURE 2 is an enlarged, fragmentary section of the dies just prior to contact of the cup edge by the downwardly moving upper die, and

FIGURES 3 and 4 are views similar to FIGURE 2 but showing the upper die in an intermediate position and at the end of its stroke, respectively.

Referring in greater detail to the drawings, several female anvils 1 each having a lower die 2 (only one shown) are circumferentially spaced around and rigidly mounted on a rotatable turret 3 for rotation therewith from one station in the machine to another where various operations are performed on the cup 4. The station shown is the rim curling station in which a curling die 5 is threaded as at 6 to the shaft 7 which is rotatably mounted in the tubular member 8 on bearings 9, and which member in turn is recipro2able with the housing 10. The member 8 is also slidably mounted with respect to and in the bore 11 of the housing 10 so that the latter can overtravel member 8. Thus, the upper die 5 is reciprocable toward and away from the stationary lower die 2 between the raised position shown in FIGURE 1 and the position shown in FIGURE 4 where the upper die has completed its downward stroke.

Although the upper die has been shown as being mounted for rotation and consequent spinning of the bead, the invention is also useable in a cold forming operation where the curler is not rotated.

The die 5 has been shown and will be described as being movable in a vertical direction although the use of terms herein such as upper, lower, or vertical are not meant to limit the invention to any particularly disposed position of operation. Furthermore, although the female anvil 15 described herein as being stationary (that is, it is not movable in an axial direction in respect to its cup, but of course is rotatable with its turret) the upper die could be stationary and the anvil axially shiftable. The important feature is that it is not necessary for both die members to be axially shiftable.

Each of the female anvils 1 have their lower die 2 rigidly secured at their top end by cap bolts 13 and are simple in form. The die 2 has a tapered wall 14 which forms a smooth extension of an internal surface wall 15' of the anvil. The angle of this wall with respectto the vertical is shown as being on the order of six degrees, which is conventional for two-piece cups, although the invention is applicable to cone cups, for example, having a greater side wall angle, or other types having a vertical wall.

The lower die may be formed integrally with the female anvil if desirable, and the lower die and its anvil may be considered to be a unitary female anvil.

The lower die also has an upper tapered surface 16 which is radially spaced outwardly from surface 14. Surface 16 is primarily a guiding surface and has been shown as being inclined about six degrees from the vertical and this angle has proved to be very satisfactory in practice. This angle may vary somewhat from this figure, but the less this angle is between this figure and a greater one, the better will be the results, as will more fully appear later. In other words, the steeper the angle of this guiding surface is, up to about six degrees from the vertical, the more desirable will be the cooperative action between the dies in guiding and curling the cup edge in the single pass bead forming operation.

The internal surface 14 and the guiding surface 16 of the lower die are connected by an upwardly facing and curved forming surface 18. The smooth surfaces 16 and 18 are diamond polished and require no serrations to aid in breaking and curling the paper. The upper end of surface 14 is cut away or relieved as defined by surface 19 which extends at an angle of about twenty degrees from the vertical so as to complement and provide sufiicient clearance for the upper die 5 now to be described in detail.

, As shown in FIGURE 4, the outer diametrical surface 21 of the upper die 2 is less than the outer diameter o the finished bead, which bead diameter lies on the vertical broken line V. In accordance with the present invention, the surface 21 can be of the same diameter as the outer diameter of the finished bead, but it is preferably smaller. A clearance angle of about six degrees is thus formed between surfaces 21 and 16. The upper die 2 also has a lower tapered surface 23 which is inclined about twenty degrees from the vertical, although this angle is not critical, and complements surface 19 spaced a slight distance therefrom when the dies are together. Surface 23 may initially guide the cup edge into sliding engagement with a curved surface 25.

The curved surface 25 connects the inclined surfaces 23 and 21, and together with the latter defines an annular pointed edge 27. Curved surfaces 18 and 25 defined the size limits of the finished bead and between which the head is tightly rolled.

As the surface 21 of the upper die lies radially within the outer diameter of the finished bead, the latter bears against the surface 16.

Operation As the upper die descends downwardly from the FIG- URE 2 position toward the stationary lower die and to the position shown in FIGURE 4, either the tapered surface 23 or the downwardly facing upper curved surface 25 (depending on the exact position of the cup edge) engages the top edge of the cup, and surface 25 then turns it outwardly and also downwardly. By the time the extreme cup edge passes the pointed edge 27, the latter has descended well below the top end of the lower die and is located within the annular surface 16. During continued downward movement of the upper die, the movement of the outer edge of the cup is closely and accurately controlled because of the closed relationship between the edge 27 of the upper die and the substantially vertical annular wall 16 of the lower die. This closed relationship exists during the bead curling operation regardless of the exact vertical relative positions between the dies and the cup edge cannot escape outwardly between the dies. The cup edge is positively moved against the wall 16 and guided into contact with and is curled inward- 1y and then upwardly by the surface 18. Upon completion of the die stroke, the outer edge of the cup has been wrapped tightly under the rest of the curled rim.

When the upper die is withdrawn from the lower die, it does not disturb or move the bead in any manner. The completed cup remains in the female anvil as the turret is rotated to the next station, and when the cup is ultimately ejected from the anvil by the plunger 30, the head has had sufficient time to cool and set.

Because the head has been hearing against the surface 16, it has been prevented from unwinding, thus insuring a tight curl. Furthermore, as the cup is ejected, the bead tends to be tightened by being pushed upwardly over surface 16 rather than tending to be unwound as in some prior art bead formers.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

What is claimed and desired to be secured by Letters Patent is:

A device for curling the edge of a container comprising, a stationary female anvil having an internal wall surface in which the container is seated and extends upwardly therefrom, said anvil having a substantially vertical annular guiding surface at its upper end and spaced radially outwardly from its internal wall surface, said anvil also having an upwardly facing curved surface joining said internal wall and guiding surfaces, an upper die having a fixed diameter not greater than the internal diameter of said guiding surface, means for effecting relative movement between said anvil and upper die between fully open and closed positions, said upper die having a downwardly facing curved surface which complements said anvil curved surface to define the diametrical limit of said curled edge when said upper die is in the fully closed position, said downwardly facing curved surface acting as it moves toward said anvil to curl said container edge outwardly and then downwardly and then cooperate with said substantially vertical guiding surface in holding said edge captive and directing it into engagement with said upwardly facing curved surface.

References Cited in the file of this patent UNITED STATES PATENTS 1,285,190 Hul'bert Nov. 19, 1918 1,467,027 Dolan Sept. 4, 1923 2,268,937 Harvey Jan. 6, 1942 2,473,836 Wixon et al June 21, 1949 2,541,905 Amberg Feb. 13, 1951 

